It is often desirable to scan people with a body scanner to detect potential contraband. For example, metal detectors and body scanners are often used to detect weapons within particular environments, such as airports. A body scanner may be used to create an image of a person and to determine if the person has secreted a weapon or other contraband on his or her body or clothing.
Body scanners are not instantaneous. It takes time for the body scanner to fully scan a person and create an image of the person. As a result, places that have many visitors often develop long lines. For example, it is not uncommon for an airport security line to take thirty minutes due in part to the amount of time it takes to scan people in the security line.